SIMULATION OF TUNGSTEN TIP-AL(100) SURFACE ELECTRONIC-STRUCTURE THROUGH LCAO-LSD CALCULATIONS

LDA-LCAO molecular orbital calculations were carried out on Various cl usters modeling a tungsten tip and an Al(100) surface interaction. The surface is depicted by Al-x aggregates (x varying from 5 to 66) while the tip is modeled by W-y clusters (y = 1, 5, 10, 14). Electronic str uctures were obtained for isolated aluminum and tungsten clusters and for interacting Al-x-W-y ones. For the latter, the W-Al equilibrium di stance was determined from the total energy results. Total and local d ensities of states were analyzed vs. cluster sizes. The occupied bandw idth, the Fermi level, and LDOS structures become stable from x equal to 25. Electronic structures obtained through the cluster description are in rather good agreement with a slab calculation for the surface u sing the same theoretical approach and with other theoretical calculat ions. The general trends of Al-W interactions are discussed. (C) 1997 John Wiley & Sons, Inc.